Final LS2 upgrade work to the ATLAS detector before cavern closure

Since the start of LS2, ATLAS has undergone an intense maintenance and consolidation programme to meet the challenges of Run 3 of the LHC, and fully exploit the available physics opportunities. This includes the installation and commissioning of new detectors and electronics thus enhancing the Level-1 trigger and rate capabilities of the experiment. Data-taking activities during the long shutdown have encompassed standalone runs of individual systems, combined runs involving several or all available systems, and cosmic-ray data taking. Moreover, ten “Milestone” weeks (i.e. combined data-taking runs with all available systems) took place during LS2 with the most recent during the LHC pilot run.